Tech Talk: Waterproof foam


Welcome to a new Tech Talk. Today we’re going to talk about our 50k waterproof foam and how it’s different from foam in other boards out there.

50k foam is similar to EPS but waterproof

So at Appletree Surfboards we use our proprietary 50k foam. The 50k foam is in the basis polystyrene, so it’s similar to an EPS foam core, but with one huge advantage and that it’s completely waterproof. And I mean 100 % waterproof. Which is very important in your board. Especially when you’re in the unlucky situation of dinging your board. 

Why is it called 50k foam?

Our 50k foam is called 50k because you can actually put 50 000 kilograms on one square meter of foam without the foam deforming. So you can imagine this foam is really strong and really hard. But at the same time it’s really nice and lightweight. 

Most other boards are made of EPS foam

EPS foam is used in almost all foil and kiteboards nowadays. The foam is made of little beads and balls, like the foam that your new TV is packed in. The individual beads are waterproof themselves, but there’s voids in between the beads. Even if they’re fused completely together, there are always voids. And that’s an open cell structure in the entire board. Now here’s the problem. 

EPS foam is not waterproof

The board is fine when it’s closed and it’s new and whole. But as soon as you put it in the sun or somewhere warm, air expands. So there is a pressure build up inside the board. This is still not a problem, as long as this pressure is sort of low. 

What happens when you have a small ding

But the problem happens when you have a small crack or a small ding in your board. Now the pressure can actually escape from the board, so the board will start to blow out air softly. If you then grab your board and run into the water, the water is always colder so the board cools down and the air compresses again. But while compressing it starts to suck back in through the hole that you have. But now the board is in the water so instead of sucking in the air, it starts to suck in water. This is what we call water logging. 

It’s super hard to get the water out

I’ve seen EPS boards that look new but are a kilo heavier. A whole liter of water has gone into the board. The biggest problem is it’s super hard to get this water out. Because the voids run all the way into the board. So the water can creep really deep into the board. And sometimes completely rendering the boards useless. Especially if you then put the board back into a hot car. It starts to expand again and the water gets sucked in even further into the board.

50k foam is completely waterproof

With our 50k foam this is guaranteed not to happen. We’ve had boards that had little cracks in them for months without any issues. A disclaimer, we always advise to get your board repaired or repair it yourself. But if you’re on a trip or if you’re riding you don’t necessarily have to exit the water straight away. You just keep on riding the board. It will be fine as long as the crack is not massive. 

So that’s some of the advantages of our 50k foam and why it’s so much better than the EPS one that’s used normally. I hope you like this video and see you next time in our next video!

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